It is known that angioplasty, arterial bypass surgery, organ transplantation, etc. frequently entail a hypertrophy and occlusion of the blood vessel owing to, inter alia, proliferation of vascular smooth muscle cells. Though much study is undergoing for finding a useful drug for the prevention and cure of the condition (e.g. J P Kohyo H3-500660), no effective drug has been discovered as yet.
Inspired by this demand for drugs effective for the prevention and cure of vascular hypertrophy, the inventors of this invention did much research and discovered that a compound of the above formula (I), which is already known to have vasodilatory and antithrombotic activities, is capable of inhibiting vascular hypertrophy. Further research has culminated in the perfection of this invention.